You also mention that you got two of them? Chances are if the guy was ill, your second one could be as well. Make sure you do a thorough cleaning of your tank and if you get another one you will need to quaratine it (3 months for wild caught and 1 month for captive bred).
Tim gave you pretty much the rundown. You need a minimum 20 gallon tank for one white's tree frogs. Add ten to that number for every additional frog. I house four in a 72 gallon. If possible, a taller tank is better than a wide as they are aboreal and like to be up high. They like lots of hiding places to sleep during the day . .I can't even see mine during the day! Then at night, they like to roam around and play.
Feeding is basically 4 - 6 crickets every other day (give or take . .you'll figure it out as you adjust to your frogs habits). This is for adults. Also, dust the crickets every third feeding (again, this is for adults). They need clean water every day and don't put the water too deep 'cause they can drown quite easily.
Wow . .I just rambled off alot of information at once. If you have any questions, let me know.
Check out my photo's on this site (it'll be under Dakhota). You'll see some pic's of my tank which could help you along if you need it.
Good Luck!